ARQ with Cumulative Feedback to Compensate for Burst Errors

TL;DR

This paper introduces a cumulative feedback ARQ protocol that improves delay and throughput in bursty and unreliable feedback channels, enhancing robustness for ultra-reliable low-latency communications in 5G.

Contribution

It presents a novel CF ARQ protocol with a matrix signal-flow graph analysis, demonstrating significant delay reduction and throughput gains over existing schemes under burst errors.

Findings

Up to 20% throughput improvement

Significantly reduced average delay

Enhanced stability and predictability

Abstract

We propose a cumulative feedback-based ARQ (CF ARQ) protocol for a sliding window of size 2 over packet erasure channels with unreliable feedback. We exploit a matrix signal-flow graph approach to analyze probability-generating functions of transmission and delay times. Contrasting its performance with that of the uncoded baseline scheme for ARQ, developed by Ausavapattanakun and Nosratinia, we demonstrate that CF ARQ can provide significantly less average delay under bursty feedback, and gains up to about 20% in terms of throughput. We also outline the benefits of CF ARQ under burst errors and asymmetric channel conditions. The protocol is more predictable across statistics, hence is more stable. This can help design robust systems when feedback is unreliable. This feature may be preferable for meeting the strict end-to-end latency and reliability requirements of future use cases of ultra-reliable low-latency communications in 5G, such as mission-critical communications and industrial control for critical control messaging.